1. Field of the Invention
The present invention relates to a multi-path valve arrangement in a beverage making unit, particularly an espresso machine by which optionally various beverages can be prepared.
2. Description of the Related Art
Prior art multi-path valve arrangements in a beverage making unit which make possible in espresso machines an optionally alternate preparation of hot milk or milk froth and cold rinsing and aeration of the milk-conducting pipes may be realized by means of solenoid valves which are either controlled by manually actuated contacts or a set, program-controlled, into either a through-connecting position or a blocking position. Such multi-part multi-path valve arrangements require a plurality of connections and connectors to the functional units controlled by them. Due to the system, the solenoid valves comprise movable mechanical elements disposed in the milk flow and hence are difficult to rinse. In view of their type of construction and the cross sections of the pipes preset by the design which can be switched to either completely through-connecting or blocked only, these solenoid magnets conduct, with identical suction power sucking the milk, always the same milk flow, unless blocked, independently from whether the milk flow is required for hot milk preparation or for milk froth preparation. Since for the preparation of hot milk a larger amount of steam, or energy, for heating the milk is required than for milk froth preparation, it is necessary that in beverage making units, particularly espresso machines, in which such a multi-path valve arrangement comprising multi-path valves has been provided, a larger amount of steam, or energy, respectively, has to be provided for heating the milk than for preparing the milk froth, which causes increased production costs. Moreover, since always the same amount of milk is heated by the steam flow which is supplied for heating during a given time but which may have different temperatures, the milk temperature will not always obtain the desired value but will be either too high or too low.
Further prior art multi-path valve arrangements each including a mechanical hand-actuated multi-path valve, as compared thereto, may be realized in a more compact structure with less terminals; as a rule, however, they permit restricted functions only, without cold rinsing and aeration of milk-conducting pipes so that undesired milk residues may remain in them.